Amj^i8P94arm-}  Economic  Botany.  283 
from  plants,  we  may  say  that  we  are  absolutely  dependent  upon 
them  for  the  essentials  of  our  diet,  and  would  quickly  perish  with- 
out them. 
We  depend  scarcely  less  upon  them  for  our  clothing  and  building 
materials,  and  for  numberless  other  things  upon  which  our  comfort 
and  well-being  depend. 
We  also  draw  from  the  vegetable  world  the  greater  part  of  the 
medicines  we  employ  in  healing  our  diseases.  There  are  also  the 
best  of  reasons  for  believing  that  if  it  were  not  for  the  chemical 
activity  of  plants  in  breaking  up  the  carbon  dioxide  so  constantly 
exhaled  into  the  atmosphere  from  the  lungs  of  animals,  from  the 
chimney  throats  of  our  factories  and  private  dwellings,  and  from 
the  processes  of  decay  that  go  on  about  us  everywhere — if  it  were 
not  for  this  and  the  restoration  of  pure  oxygen  to  the  atmosphere 
that  the  chlorophyll  plants  are  all  the  time  accomplishing,  the 
atmosphere  itself  would  soon  become  so  vitiated  that  it  could  no 
longer  sustain  the  higher  forms  of  animal  life,  and  we  should  perish 
from  the  earth. 
In  still  another  respect,  we  are  dependent  on  this  world  of  plants. 
If  it  were  not  for  the  bacteria  and  fungi,  those  despised  and  very 
much  dreaded  parasitic  and  saprophytic  organisms  whose  work  is 
largely  that  of  tearing  down  and  restoring  to  the  mineral  kingdom, 
and  so  to  available  forms  for  growth,  dead  organic  bodies,  the 
earth  would  soon  be  piled  so  high  with  corpses  that  there  would 
be  neither  room  nor  sustenance  for  living  beings. 
It  is  largely  on  account  of  these  relations  between  plants  and 
human  welfare  that  botany,  the  science  of  plants,  has  grown  up. 
True,  superstition  has  had  something  to  do  with  its  beginnings,  as 
it  has  with  those  of  other  sciences,  chemistry  and  astronomy,  for 
example.  The  superstitious  belief  in  a  philosopher's  stone  stimu- 
lated the  research  which  gathered  together  many  important  facts 
that  have  greatly  helped  to  lay  the  foundation  of  chemical  science. 
Likewise,  it  was  a  superstition  that  the  stars  sway  the  destinies  of 
men,  but  it  stimulated  observation  of  the  heavenly  bodies  and  aided 
to  accumulate  the  facts  on  which  rests  the  superstructure  of  modern 
astronomy.  So,  in  botany,  for  example,  the  absurd  doctrine  of  sig- 
natures, which  so  long  prevailed  in  medicine,  led  to  a  decided  exten- 
sion of  our  knowledge  of  plants,  and  so  helped  build  a  science  of 
botany. 
